APPENDIX II 73 



Every object must be clean, dry, and cool before 

 weighing. On removing crucibles from heating over 

 lamps, or objects from heating in a water -bath, they 

 are best placed under a bell-jar on a glass plate, and a 

 little dish of strong sulphuric acid should be placed 

 under the bell-jar beside them, or they may be placed in 

 an ordinary desiccator instead. 



NOTE 



For a class of twenty pupils, one balance and two drying 

 ovens will be sufficient. Certain experiments, such as 13, 18, 20, 

 25, 30, 31, 32, are best performed by the teacher before the class. 

 The rest should be performed by the pupils themselves. In the 

 list of apparatus those marked with a star should be provided for 

 each pupil. One set of the other things will be sufficient. 



